... For instance, PepsiCo recently acquired Gatorade and Sobe functional beverage brands; Heinz a... more ... For instance, PepsiCo recently acquired Gatorade and Sobe functional beverage brands; Heinz acquired a share in Hain Foods, a processor of soy and natural foods; and Quaker and Novartis entered into a joint venture to form Altus Food Company, which is dedicated to the ...
ABSTRACT HPP benefits have led to increasing commercial production of HP preserved foods.•Microor... more ABSTRACT HPP benefits have led to increasing commercial production of HP preserved foods.•Microorganism inactivation by HPP in complex food matrices is reviewed.•Emphasis is set on inactivation mechanisms in low or non-uniform aw products.•aw alone is not sufficient to explain disparities in inactivation.•Matrix specificities must be considered in addition to aw protection effect.
... Research work on feasibility of a PEF treatment in meat processing is currently performed at ... more ... Research work on feasibility of a PEF treatment in meat processing is currently performed at Berlin University of Technology, it was shown that the fermentation of raw sausages (Salami type) can be accelerated by improving the availability of intracellular liquid for fermenting ...
A continuously working pilot plant-scale prototype was used to evaluate the effects of continuous... more A continuously working pilot plant-scale prototype was used to evaluate the effects of continuous-flow ultrasound-temperature treatment for bacterial decontamination of model suspensions and various liquid food systems such as milk, fruit, and vegetable juices. Escherichia coli K12 DH 5 alpha and Lactobacillus acidophilus were used as test microorganisms. In addition, treated juices were investigated for damage caused by heat or ultrasound-induced degradation of sensory and nutritional properties after treatment and storage. Changes in color and destruction of heat-labile and slightly oxidizable L-ascorbic acid content were monitored as an index to measure processing effects. Results were assessed with respect to the total energy requirement and compared with those using a conventional, indirect heating method having similar processing conditions. For the bacteriological process evaluation, the temperature- and time-dependent process lethality was used as the basis; for the quality-...
Nitrate is a natural constituent of the human diet and an approved food additive. It can be parti... more Nitrate is a natural constituent of the human diet and an approved food additive. It can be partially converted to nitrogen monoxide, which induces vasodilation and thereby decreases blood pressure. This effect is associated with a reduced risk regarding cardiovascular disease, myocardial infarction, and stroke. Moreover, dietary nitrate has been associated with beneficial effects in patients with gastric ulcer, renal failure, or metabolic syndrome. Recent studies indicate that such beneficial health effects due to dietary nitrate may be achievable at intake levels resulting from the daily consumption of nitrate-rich vegetables. N-nitroso compounds are endogenously formed in humans. However, their relevance for human health has not been adequately explored up to now. Nitrate and nitrite are per se not carcinogenic, but under conditions that result in endogenous nitrosation, it cannot be excluded that ingested nitrate and nitrite may lead to an increased cancer risk and may probably be carcinogenic to humans. In this review, the known beneficial and detrimental health effects related to dietary nitrate/nitrite intake are described and the identified gaps in knowledge as well as the research needs required to perform a reliable benefit/risk assessment in terms of long-term human health consequences due to dietary nitrate/nitrite intake are presented.
ABSTRACT The comparison between technologies was performed based on microbial equivalence•Industr... more ABSTRACT The comparison between technologies was performed based on microbial equivalence•Industrial scale HPP and pilot scale PEF and thermal units were used•The effect of storage on the fingerprint of tomato juice was taken into account•All pasteurisation technologies caused loss of several volatiles compared to control•All technologies caused the increase of Z-citral and 6-methyl-5-hepten-2-one•Fatty acids, carotenoids and amino acids degradation were observed
ABSTRACT A new generation of high pressure homogenizers reaching up to 400 MPa offers opportuniti... more ABSTRACT A new generation of high pressure homogenizers reaching up to 400 MPa offers opportunities for spore inactivation and high pressure sterilization of foods. A Stansted Fluid Power ultra-high pressure homogenization (UHPH) unit was tested to inactivate bacterial spores in a model buffer system. Bacillus subtilis PS832 and Geobacillus stearothermophilus ATCC7953 spores’ thermal resistances were assessed (D, z-value and Ea). The pressure and valve temperature were monitored during UHPH. Residence times under pressure and high temperature were estimated and enabled comparison with thermal inactivation, indicating the estimated thermal contribution to inactivation. Spore germination was also assessed but no germination was observed. Up to five log10B. subtilis and two log10G. stearothermophilus spores were inactivated by the harshest treatments (> 300 MPa –Tvalve > 145 °C for ~ 0.24 s). The inactivation profiles were similar to the predicted thermal inactivation suggesting that the valve temperature might be a dominant parameter leading to bacterial spore inactivation.
The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telesc... more The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train, in this case the secondary 1.1m mirror, and four Laser Guide Stars (LGSs). This evolution implements many challenging technologies like the Deformable Secondary Mirror (DSM) including a thin
The preservation of low-acid canned food to achieve non-refrigerated, shelf-stable products requi... more The preservation of low-acid canned food to achieve non-refrigerated, shelf-stable products requires the elimination of vegetative microbial cells as well as the inactivation of bacterial endospores capable of growing in the product at the conditions prevailing during distribu-tion and ...
In excess of a critical transmembrane potential ΔϕM of −1 V produced by high intensity pulsed ele... more In excess of a critical transmembrane potential ΔϕM of −1 V produced by high intensity pulsed electric fields a rapid electrical breakdown and local conformational changes of cell membranes occur which result in a drastic increase in permeability and an equilibration of the electrochemical and electrical potential differences of the cell plasma and the extracellular medium. As irreverible membrane permeabilization
The mechanism of inactivation of bacterial spores by heat and pressure is still a matter of discu... more The mechanism of inactivation of bacterial spores by heat and pressure is still a matter of discussion. Obviously, the change of the dissociation equilibrium under pressure and temperature plays a dominant role in inactivation of microorganisms. Heat and pressure inactivation of Geobacillus. stearothermophilus spores at different initial pH-values in ACES and phosphate buffer confirmed this view. Thermal inactivation in ACES buffer at 122°C resulted in higher logarithmic reductions. Contrary, after pressure treatment at 900 MPa with 80°C phosphate buffer showed higher inactivation. These results indicated the different dissociation equilibrium shifts in buffer systems by heat and pressure. Due to preparation, storage and handling of highly concentrated spore suspensions the clumping and the formation of aggregates can hardly be avoided. Consequently, the impact of the agglomeration size distribution on the quantitative assessment of G. stearothermophilus spore inactivation was determined by using a three-fold dynamic optical backreflexion measurement. Two limiting cases have been discriminated in mathematical modelling: three dimensional, spherical packing for maximum spore count and two dimensional, circular packing for minimum spore count of a particular agglomerate. Thermal inactivation studies have been carried out in thin glass capillaries, where by using numerical simulations the non isothermal conditions were modelled and taken into account. It is shown that the shoulder formation often found in thermal spore inactivation can sufficiently be described by first-order inactivation kinetics when the agglomeration size is considered. In case of high pressure inactivation agglomerations could be strongly changed by high forces at compression and especially decompression phase. The physiological response of Bacillus licheniformis spores to high pressure was investigated using multiparameter flow cytometry. Spores were treated by high pressure at 150 MPa with 37°C, and then dual stained with the fluorescent dyes SYTO 16 and propidium iodide. For pressure treated spores four distinct populations were detected by flow cytometry, and for these we suggest a three step model of inactivation involving a germination step following hydrolysis of the spore cortex, an unknown step, and finally an inactivation step with physical compromise of the spore inner membrane. An understanding of these effects and mechanisms will aid the safety assessment of pressure assisted thermal sterilisation, in turn facilitating the adoption by industry and commercialisation of such processes.
... For instance, PepsiCo recently acquired Gatorade and Sobe functional beverage brands; Heinz a... more ... For instance, PepsiCo recently acquired Gatorade and Sobe functional beverage brands; Heinz acquired a share in Hain Foods, a processor of soy and natural foods; and Quaker and Novartis entered into a joint venture to form Altus Food Company, which is dedicated to the ...
ABSTRACT HPP benefits have led to increasing commercial production of HP preserved foods.•Microor... more ABSTRACT HPP benefits have led to increasing commercial production of HP preserved foods.•Microorganism inactivation by HPP in complex food matrices is reviewed.•Emphasis is set on inactivation mechanisms in low or non-uniform aw products.•aw alone is not sufficient to explain disparities in inactivation.•Matrix specificities must be considered in addition to aw protection effect.
... Research work on feasibility of a PEF treatment in meat processing is currently performed at ... more ... Research work on feasibility of a PEF treatment in meat processing is currently performed at Berlin University of Technology, it was shown that the fermentation of raw sausages (Salami type) can be accelerated by improving the availability of intracellular liquid for fermenting ...
A continuously working pilot plant-scale prototype was used to evaluate the effects of continuous... more A continuously working pilot plant-scale prototype was used to evaluate the effects of continuous-flow ultrasound-temperature treatment for bacterial decontamination of model suspensions and various liquid food systems such as milk, fruit, and vegetable juices. Escherichia coli K12 DH 5 alpha and Lactobacillus acidophilus were used as test microorganisms. In addition, treated juices were investigated for damage caused by heat or ultrasound-induced degradation of sensory and nutritional properties after treatment and storage. Changes in color and destruction of heat-labile and slightly oxidizable L-ascorbic acid content were monitored as an index to measure processing effects. Results were assessed with respect to the total energy requirement and compared with those using a conventional, indirect heating method having similar processing conditions. For the bacteriological process evaluation, the temperature- and time-dependent process lethality was used as the basis; for the quality-...
Nitrate is a natural constituent of the human diet and an approved food additive. It can be parti... more Nitrate is a natural constituent of the human diet and an approved food additive. It can be partially converted to nitrogen monoxide, which induces vasodilation and thereby decreases blood pressure. This effect is associated with a reduced risk regarding cardiovascular disease, myocardial infarction, and stroke. Moreover, dietary nitrate has been associated with beneficial effects in patients with gastric ulcer, renal failure, or metabolic syndrome. Recent studies indicate that such beneficial health effects due to dietary nitrate may be achievable at intake levels resulting from the daily consumption of nitrate-rich vegetables. N-nitroso compounds are endogenously formed in humans. However, their relevance for human health has not been adequately explored up to now. Nitrate and nitrite are per se not carcinogenic, but under conditions that result in endogenous nitrosation, it cannot be excluded that ingested nitrate and nitrite may lead to an increased cancer risk and may probably be carcinogenic to humans. In this review, the known beneficial and detrimental health effects related to dietary nitrate/nitrite intake are described and the identified gaps in knowledge as well as the research needs required to perform a reliable benefit/risk assessment in terms of long-term human health consequences due to dietary nitrate/nitrite intake are presented.
ABSTRACT The comparison between technologies was performed based on microbial equivalence•Industr... more ABSTRACT The comparison between technologies was performed based on microbial equivalence•Industrial scale HPP and pilot scale PEF and thermal units were used•The effect of storage on the fingerprint of tomato juice was taken into account•All pasteurisation technologies caused loss of several volatiles compared to control•All technologies caused the increase of Z-citral and 6-methyl-5-hepten-2-one•Fatty acids, carotenoids and amino acids degradation were observed
ABSTRACT A new generation of high pressure homogenizers reaching up to 400 MPa offers opportuniti... more ABSTRACT A new generation of high pressure homogenizers reaching up to 400 MPa offers opportunities for spore inactivation and high pressure sterilization of foods. A Stansted Fluid Power ultra-high pressure homogenization (UHPH) unit was tested to inactivate bacterial spores in a model buffer system. Bacillus subtilis PS832 and Geobacillus stearothermophilus ATCC7953 spores’ thermal resistances were assessed (D, z-value and Ea). The pressure and valve temperature were monitored during UHPH. Residence times under pressure and high temperature were estimated and enabled comparison with thermal inactivation, indicating the estimated thermal contribution to inactivation. Spore germination was also assessed but no germination was observed. Up to five log10B. subtilis and two log10G. stearothermophilus spores were inactivated by the harshest treatments (> 300 MPa –Tvalve > 145 °C for ~ 0.24 s). The inactivation profiles were similar to the predicted thermal inactivation suggesting that the valve temperature might be a dominant parameter leading to bacterial spore inactivation.
The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telesc... more The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train, in this case the secondary 1.1m mirror, and four Laser Guide Stars (LGSs). This evolution implements many challenging technologies like the Deformable Secondary Mirror (DSM) including a thin
The preservation of low-acid canned food to achieve non-refrigerated, shelf-stable products requi... more The preservation of low-acid canned food to achieve non-refrigerated, shelf-stable products requires the elimination of vegetative microbial cells as well as the inactivation of bacterial endospores capable of growing in the product at the conditions prevailing during distribu-tion and ...
In excess of a critical transmembrane potential ΔϕM of −1 V produced by high intensity pulsed ele... more In excess of a critical transmembrane potential ΔϕM of −1 V produced by high intensity pulsed electric fields a rapid electrical breakdown and local conformational changes of cell membranes occur which result in a drastic increase in permeability and an equilibration of the electrochemical and electrical potential differences of the cell plasma and the extracellular medium. As irreverible membrane permeabilization
The mechanism of inactivation of bacterial spores by heat and pressure is still a matter of discu... more The mechanism of inactivation of bacterial spores by heat and pressure is still a matter of discussion. Obviously, the change of the dissociation equilibrium under pressure and temperature plays a dominant role in inactivation of microorganisms. Heat and pressure inactivation of Geobacillus. stearothermophilus spores at different initial pH-values in ACES and phosphate buffer confirmed this view. Thermal inactivation in ACES buffer at 122°C resulted in higher logarithmic reductions. Contrary, after pressure treatment at 900 MPa with 80°C phosphate buffer showed higher inactivation. These results indicated the different dissociation equilibrium shifts in buffer systems by heat and pressure. Due to preparation, storage and handling of highly concentrated spore suspensions the clumping and the formation of aggregates can hardly be avoided. Consequently, the impact of the agglomeration size distribution on the quantitative assessment of G. stearothermophilus spore inactivation was determined by using a three-fold dynamic optical backreflexion measurement. Two limiting cases have been discriminated in mathematical modelling: three dimensional, spherical packing for maximum spore count and two dimensional, circular packing for minimum spore count of a particular agglomerate. Thermal inactivation studies have been carried out in thin glass capillaries, where by using numerical simulations the non isothermal conditions were modelled and taken into account. It is shown that the shoulder formation often found in thermal spore inactivation can sufficiently be described by first-order inactivation kinetics when the agglomeration size is considered. In case of high pressure inactivation agglomerations could be strongly changed by high forces at compression and especially decompression phase. The physiological response of Bacillus licheniformis spores to high pressure was investigated using multiparameter flow cytometry. Spores were treated by high pressure at 150 MPa with 37°C, and then dual stained with the fluorescent dyes SYTO 16 and propidium iodide. For pressure treated spores four distinct populations were detected by flow cytometry, and for these we suggest a three step model of inactivation involving a germination step following hydrolysis of the spore cortex, an unknown step, and finally an inactivation step with physical compromise of the spore inner membrane. An understanding of these effects and mechanisms will aid the safety assessment of pressure assisted thermal sterilisation, in turn facilitating the adoption by industry and commercialisation of such processes.
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